The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
There are known internal combustion engines for motor vehicles comprising a head bearing one or more cylinders, within which the work cycle is carried out, and which are placed in communication with respective combustion chambers of the engine itself. On the above mentioned head, there are further obtained appropriate seats intended to let the combustion chamber communicate with ducts adapted to supply a mixture of unburnt fuel and air to said chamber (“suction ducts”), and discharge the burnt gases from said combustion chamber (“discharge ducts”).
The flows from and to each combustion chamber are controlled by appropriate valves operating on the mentioned seats. Specifically, each valve generally comprises a guide element fixed within a cavity of the engine head and a slidingly displaceable rod in opposite directions within a through seat defined by the guide element and bearing, at one end, a clogging section to close the connection between the relative suction or discharge duct and the corresponding combustion chamber.
The opposite end of the rod of the valve axially protrudes from the relative guide element and is adapted to receive driving forces from a relative control device.
On the valves of the above described type, there are normally mounted seal gaskets for the lubricating oil normally circulating in the engines. Such gaskets, in one of the most commonly known forms, comprise a support or reinforcing element having a substantially tubular configuration, generally made of a metal material, and an element made of elastomeric material interposed between the support element and the valve.
Specifically, the elastomeric element typically comprises a first portion adapted to cooperate by means of its inner surface with the outer surface of the upper portion of the guide element, and a second portion adapted to directly cooperate with the rod of the valve.
The gaskets of the above described type are widely used in all internal combustion engines to control the amount of lubricating oil that flows from the distribution area towards the combustion chambers. An excessive flow of lubricating oil causes a deterioration in the efficiency of the engine and a drop in the performance of the motor vehicle catalytic converter as well as an evident excessive consumption of the oil itself. On the other hand, an insufficient flow determines an increase in the wear and the noise of the valves together with the occurrence of local temperature peaks. These phenomena may determine a premature damage of the valves following the seizure of the rod of the valves themselves within the guide element.
The known gaskets allow the construction of a static-type seal by means of the first portion of the elastomeric element operating on the guide element of the relative valve, and the construction of a dynamic-type seal by means of the second portion of the elastomeric element cooperating with the rod. Specifically, the static seal must ensure a certain degree of radial compression on the guide element in order to avoid the throttling of the lubricating oil to the combustion chambers and at the same time maintain the gasket itself in position, whereas the dynamic seal is designed to allow the minimum flow of oil required for the lubrication of the coupling between rod and guide element.
The support element comprises a first substantially cylindrical portion and a second discoidal annular portion, extending from an axial end of the first portion towards the valve in a transversal direction with respect to the axis of the first portion itself; such a second portion is partially drowned in the elastomeric element.
The applicant has noted that, in use, the cyclic stresses which the elastomeric element is subjected to may determine, in its annular seat housing the second portion of the support element, a concentration of stresses with the possible fatigue cracking of the elastomeric element itself.
The present disclosure provides a gasket for a valve in an internal combustion engine, which overcomes the drawbacks related to the gaskets of the known and above specified type in a simple and cost-effective manner.
The present disclosure refers to a gasket for a valve in an internal combustion engine, comprising: a support element having a tubular configuration according to an axis and coaxially mounted on said valve; and an elastically deformable element interposed between said support element and said valve; said support element comprising a first portion elongated according to said axis, and a second portion extending from said first portion in a direction transversal to said axis, at least partially housed in an annular seat of said elastically deformable element and having its radially outermost end connected to the first portion itself, wherein said support element comprises a third portion extending from the radially innermost end of said second portion and folded on the second portion itself so as to generate, in the folding area, a rounded edge cooperating with said annular seat of said elastically deformable element.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.